A transgenic animal is defined as an animal having an exogenous gene introduced into the germinal line of the animal or an ancestor thereof, typically in the initial (usually single-cell) developmental stage.
Wagner et al. (Proc. Nat. Acad. Sc. U.S.A., Vol. 78, p. 5016, 1981) and Stewart et al. (Science, Vol. 217, p. 1046, 1982) described a transgenic mouse containing the human globin gene. Constantini et al. (Nature, Vol. 294, p. 92, 1981) and Lacy et al. (Cell, Vol. 34, p. 343, 1983) described a transgenic mouse containing the rabbit globin gene. McKnight et al. (Cell, Vol. 34, p. 335, 1983) described a transgenic mouse containing the transferrin gene. Brinstar et al. (Nature, Vol. 306, p. 332, 1983) described a transgenic mouse containing a functionally transfected immunoglobulin gene. Palmiter et al. (Nature, Vol. 300, p. 611, 1982) described a transgenic mouse containing the rat growth hormone gene ligated to a heavy metal-induced metallothionein promoter sequence. Palmiter et al. (Cell, Vol. 29, p. 701, 1982) described a transgenic mouse containing the thymidine kinase gene ligated to a metallothionein promoter sequence. Palmiter et al. (Science, Vol. 222, p. 809, 1983) described a transgenic mouse containing the human growth hormone gene ligated to a metallothionein promoter sequence.
Matsushima et al. (J. Exp. Med., Vol. 169, p. 1485, 1987) described a polypeptide factor showing chemotaxis for neutrophils referred to a interleukin 8 (generally abbreviated IL-8); Since then, a large number of genes that are specifically expressed in similarly activated lymphocytes etc. have been cloned. These factors called chemokines, which mean cytokines showing chemotaxis for a particular form of leukocytes.
The monocyte chemotactic and activating factor (which is now called MCP-1), a chemokine, was for the first time isolated from a human monocytic leukemia cell line (THP-1) by Matsushima et al. (J. Exp. Med., Vol. 169, p. 1485, 1989), followed by successful cloning of the cDNA thereof. Separately, Yoshimura et al. (J. Exp. Med., Vol. 169, p. 1449, 1989) isolated the monocyte chemotactic and activating factor from a human glioma cell line (U-105MG) and subsequently succeeded in cloning the cDNA thereof. Matsushima et al. and Yoshimura et al. designated this factor as the monocyte chemotactic and activating factor (generally abbreviated MCAF) and monocyte chemoattractant protein (generally abbreviated MCP-1), respectively. This factor is also called MCAF/MCP-1 to represent both designations.
MCAF/MCP-1 is a basic heparin-binding polypeptide that belongs to a subfamily of C-C chemokines (also referred to as .beta. chemokines), which are characterized by the presence of 4 cysteins, including 2 mutually adjoining cysteins, in the molecular structure thereof. Regarding the genetic structure thereof, it is known that the propeptide moiety, consisting of 23 amino acids at the amino acid terminus (generally abbreviated N-terminus), is cleaved after translation, resulting in the formation and secretion of a mature protein consisting of 76 amino acids. It is about 8.7 kD in size and is rich in the basic amino acids lysine and arginine having 2 S-S bonds; according to Zhang et al. (Mol. Cell Biol., Vol. 15, p. 4851, 1995), its biological activity results from dimerization.
A mouse gene previously known as the JE gene, reported by Rollins, B. J. et al. (Proc. Nat. Acad. Sc. U.S.A., Vol. 85, p. 3738, 1988), was reestablished as the cDNA homologous to the human monocyte chemotactic and activating factor gene. Yoshimura et al. (Biochem. Biophys. Res. Commun., Vol. 174, p. 504, 1991) reported on the homologous cDNA in the rat.
The monocyte chemotactic and activating factor gene is located on the human 17th chromosome or the mouse 4th chromosome, it consists of 3 exons and 2 introns, includes a transcription factor-binding site 5' upstream of AP-1, AP-2, NF-.sub..kappa. B, NF-IL6 etc. and the ATTTA motif in the 3' non-translational region. Also, base substitutions in its cDNA are known.
The monocyte chemotactic and activating factor is known to be produced upon stimulation by TNF-.alpha. or lipopolysaccharide (generally abbreviated LPS). Currently known biological activities of the monocyte chemotactic and activating factor include (1) chemotaxis promotion, (2) lysosome enzyme production and release, (3) IL-1 and IL-6 production promotion, (4) antitumor activity enhancement, and (5) adhesive molecule (CD11b/c) expression promotion. The monocyte chemotactic and activating factor is also known to have biological activities on basophils, including (1) chemotaxis promotion, (2) histamine release promotion, and (3) degranulation. Furthermore, the monocyte chemotactic and activating factor is known to serve as a T-cell chemotactic factor; Duboi, P. M. et al. (J. Immunol., Vol. 156, p. 1356, 1996) reported that the monocyte chemotactic and activating factor causes MAP kinase activation; del Pozo, M. A. et al. (J. Cell Biol., Vol. 131, p. 495, 1995) reported that the monocyte chemotactic and activating factor, along with the RANTES (regulated upon activation, normal T expressed and presumably secreted) C-C chemokine, induces T-cell process formation and cell surface CAM3 re-distribution; the signal transmission mechanism of the monocyte chemotactic and activating factor is also being extensively studied.
In addition, there are 13,000 monocyte chemotactic and activating factor receptors on the monocyte, which receptors have an affinity of 0.26 nM Kd value; the cDNA of this receptor was cloned by Charo et al. (Proc. Nat. Acad. Sc. U.S.A., Vol. 91, p. 2752, 1994). Structural analysis demonstrated that this cDNA is a G protein-binding type receptor having 7 transmembrane sites and that 2 receptor isoforms occur due to alternative splicing at the carboxyl terminus. These isoforms are C-C chemokine receptor type 2A (generally called CCCK2A, CCR2A or CCR2) and type 2B (generally called CCCK2B, CCR2B or CCR2). These receptors are known to possess affinity for monocyte chemoattractant protein-2 (generally called MCP-2), monocyte chemoattractant protein-3 (generally called MCP-3) monocyte chemoattractant protein-4 and monocyte chemoattractant protein-5 (generally called MCP-4 and MCP-5) (Luster, A. D. The New England Journal of Medicine, Vol., 338, page 436, 1998) as well, and showed 51% homology to previously cloned C-C chemokine receptor type 1 (generally called CCCK1, CCR.sub.1 or CCR1).
Monteclaro et al. (The Journal of Biological Chemistry, Vol. 272, p. 23186, 1996) conducted a ligand-binding experiment and identified a 35-amino terminus as an essential region with high binding capability.
Using cells transformed with the gene for said receptor, it has been shown that transfection with said gene increases calcium concentration with dependency on MCP-1 concentration and promote MAP kinase activation. Also, induction of formation of T cell projections and re-distribution of the cell surface adhesion molecule ICAM-3 was reported by del Pozo et al. (Journal of Cell Biology, Vol. 131, p. 495, 1995.
Frade et al. (The Journal of Clinical Investigation, Vol. 100, p. 497, 1997) examined the effects of MCP-1 and monoclonal antibody against said receptor on the replication of the human immunodeficiency virus type 1 (generally called HIV-1) in monocytes, and found that HIV-1 was suppressed by the monoclonal antibody against the receptor's amino terminus, as well as by MCP-1. They suggested that said receptor and C-C chemokine receptor type 5 (generally called CCCK5, CCR.sub.5 or CCR5) both act as common receptors in M.T tropic HIV-1 infection.
Smith et al. (Science, Vol. 277, p. 959, 1997) demonstrated that a variation of the 64th amino acid, valine, in said receptor to isoleucine does not affect HIV-1 infection but the progression of acquired immunodeficiency syndrome (generally called AIDS) is delayed by 2 to 4 years in those with HIV-1 infection in comparison to other patients. In addition, they showed that 28-29% of long survivors with AIDS have a deficiency of C-C chemokine receptor type 5 or a variation in the 64th amino acid.
However, Michael et al. (Nature Medicine, Vol. 3, p. 1160, 1997) showed that amino acid variation in said receptor does not change HIV-1 growth in plasma, suggesting that the variation does not affect the progression of AIDS.
The mouse monocyte chemotactic and activating factor receptor (generally called JE receptor) was for the first time cloned by Boring et al. (Journal of Biological Chemistry, Vol. 271, p. 7551). The JE receptor, which encodes 373 amino acids, was suggested as having 7 transmembrane sites, judging from its hydrophobicity, and showed 75% homology to the human monocyte chemotactic and activating factor receptor. Its carboxyl terminus, in particular, showed 81% homology to C-C chemokine receptor type 2B.
Regarding a monocyte chemotactic and activating factor receptor, the same authors (Boring et al., The Journal of Clinical Investigation, Vol. 100, p. 2552, 1997) created a mouse lacking the gene therefor. Although that homo-deficient mouse grew normally, monocyte chemotactic response to a monocyte chemotactic and activating factor (MCP-1) was reduced. In addition, in comparison with normal animals, that mouse had decreased granulocyte size due to dramatic reduction in interferon .gamma. in lymph nodes, demonstrating that said gene plays an important role in the sensitivity and production of Th-1 type cytokines.
Although there are no known homologues of said receptor other than in the mouse, Bonini et al. (DNA and Cell Biology, Vol. 16, p. 1249, 1997) cloned a receptor (CCR10) having high bindability to human MCP-1 and MCP-3. The same authors (Bonini et al., DNA and Cell Biology, Vol. 16, p. 1023, 1997) cloned a receptor (rCCR10rR) having high bindability to human MCP-1 and MIP-1.beta. in the rat. For this rCCR10rR, expression at the RNA level was noted in the heart, brain, spleen, lungs, liver and muscles.
Although 2 other receptors are known to possess affinity for monocyte chemotactic and activating factors, i.e., C-C chemokine receptor type 4 (generally called CCCK4) and Duffy antigen/chemokine receptor (generally called DARC), the differences in their ligand-receptor interaction remain unknown.
A correlation with expression of monocyte chemotactic and activating factors has been reported in such diseases as tuberculous pleurisy, fibroid lung, rheumatoid arthritis, glomerular nephritis, IgA nephropathy, arteriosclerosis and psoriasis. In hyperlipidemia and arteriosclerosis, expression of monocyte chemotactic and activating factors in arterial medial smooth muscle cells, intimal macrophages and vascular endothelial cells has been reported, with a report concluding that monocyte chemotactic and activating factors play a roll in the suppression of vascular smooth muscle cell proliferation.
Expression of monocyte chemotactic and activating factor mRNA is seen in the cardiac muscle of chronic heart failure patients (Seino et al., Cytokine, Vol. 7, p. 301, 1995); expression of monocyte chemotactic and activating factor mRNA is also known to increase in the blood of acute heart failure patients as well. Matsushima, K. et al. (FASEB J., Vol. 10, p. 1418, 1996) showed that the MCP-1 neutralization antibody improves the pathologic state in a rat acute glomerular nephritis model. Association with infectious diseases, allergic diseases, bone diseases, sepsis, chronic gingivitis, dementia, traumatic cerebral disorders (Glabinski, A. R. et al., Journal of Immunology, Vol. 156, p. 4363, 1996) etc. has also been suggested.
Regarding monocyte chemotactic and activating factor transgenic mice, the following reports are available: Nakamura, K. et al. (J. Invest. Dermatol., Vol. 105, p. 635, 1995) reported that monocyte infiltration was observed histologically in a mouse transfected with the JE gene, that showed expression of the gene in the skin. Rutledge, B. et al. (Journal of Immunology, Vol. 155, p. 4838, 1995) reported that the JE gene-transformed mouse is highly sensitive to Listeria and Mycobacterium. Fuentes, M. E. et al. (Journal of Immunology, Vol. 155, p. 5769, 1995) reported that the number of monocytes increased in mice transfected with the JE gene, and showed expression of the gene in the thymus and brain. In addition, Grewal, I. S. et al. (Journal of Immunology, Vol. 159, p. 401, 1997), who worked in a group in cooperation with Fuentes et al., created a JE gene-transformed mouse showing expression of that gene in islets, and also created a mouse transformed with both genes by crossing with the mouse of Fuentes et al. However, almost no cell infiltration was observed in islets.
Iwabuchi et al. (Proceedings of the 1995 Assembly of the Japanese Society for Immunology) created a human monocyte chemotactic and activating factor transgenic mouse, confirmed expression of the gene in the thymus, spleen, liver and testis, and detected the human monocyte chemotactic and activating factor at a blood concentration of 11,492 pg/ml. Gunn, M. D. et al. (Journal of Immunology, Vol. 158, p. 376, 1997) reported that human monocyte chemotactic and activating factor transgenic animals had that factor expressed in type II pulmonary alveolar epithelium and bronchial epithelium, with increased counts of leukocytes, monocytes and T cells in pulmonary alveoli.
There have been no reports on animals transformed with a gene for a monocyte chemotactic and activating factor receptor or those transformed with both genes for a monocyte chemotactic and activating factor and a monocyte chemotactic and activating factor receptor.